Beta-lactam compounds are a group of chemical entities containing a beta-lactam ring, namely a cyclic amide composed of three carbon atoms and one nitrogen atom. The beta-lactam ring is part of the structure of several antibiotic families, the principal ones being the penicillins, cephalosporins, carbapenems and monobactams, which are therefore referred to as beta-lactam antibiotics. These antibiotics generally work by inhibiting bacterial cell wall synthesis, thereby leading to a weakened cell wall and osmotic lysis of the bacterial cell. Bacteria can, however, become resistant to beta-lactam antibiotics, for example, by producing enzymes which hydrolyze the beta-lactam moiety and render the antibiotic inactive. These enzymes are generally referred to as beta-lactamases.
Beta-lactam compounds also include compounds that do not have direct anti-bacterial activity, but function as inhibitors of beta-lactamase enzymes and are typically combined with beta-lactam antibiotics to overcome bacterial resistance to the antibiotics. Clinically approved beta-lactamase inhibitors include, for example, clavulanic acid, which is given in conjunction with amoxicillin or ticarcillin (belong to the penicillin family).
It was initially thought that beta-lactam antibiotics would not be able to directly affect mammalian cells, since mammalian cells do not produce cell walls. However, theoretically, beta-lactam compounds might bind eukaryotic cellular proteins and affect their functions. Indeed, screening of various compounds in models of amyotrophic lateral sclerosis led to the discovery that beta-lactam antibiotics could increase the expression of neuronal glutamate transporter in cultured mammalian cells. Moreover, ceftriaxone (of the cephalosporin family) was found to protect animals from several forms of glutamate-induced toxicity (Rothstein et al. (2005) Nature 433, 73-77).
Previous reports have addressed the possibility of penicillin binding to plasma proteins, which was suspected as the initial step in the sequence of events leading to adverse hypersensitivity reactions associated with this antibiotic. For example, Christie et al. (1987) Biochem Pharmacol, 36, 3379-3385 have synthesized a conjugate of albumin and benzylpenicillin (also known as penicillin G), and investigated its disposition and metabolism. Bertucci et al. (2001) Biochim Biophys Acta, 1544, 386-392 have studied structural and binding properties of albumin modified with penicillin G.
The conventional antibacterial properties of beta-lactam antibiotics are utilized in the treatment of cancer patients. Specifically, these compounds are often indicated for treating neutropenic cancer patients receiving chemotherapy or radiation therapy, which are prone to bacterial infections due to immunodeficiency.
Several classes of beta-lactam compounds have been shown to possess anti-cancer properties (reviewed in Kuhn et al. (2004) Front Biosci., 9:2605-17). For example, N-thiolated beta-lactam compounds, also referred to as N-thiolated monobactams, have been found to induce tumor cell apoptosis. The 4-alkylidene-betalactams have been shown to inhibit matrix metalloproteinases essential for tumor-induced neovascularization. Beta-lactam compounds with polyaromatic substituents have been shown to induce tumor cell death in a variety of cancer cell lines, and slow or inhibit tumor cell growth in vivo.
Cornman (1944) J Gen Physiol., 28(2):113-8 has reported about a selective lethal effect of an agent present in a penicillin preparation towards rat and mouse sarcoma cells, which was observed when these cells were grown with normal cells in tissue cultures. However, subsequent work (Lewis (1944) Science, 100; 314) has ruled out the involvement of penicillin in this effect, showing that it was not exerted by highly purified colorless penicillin, but rather due to some substance present in the less purified samples along with the bacteriostatic factor. Moreover, penicillin, as well as other beta-lactam antibiotics, is routinely and widely used in cell cultures, including cancer cell culture, to prevent bacterial contamination of the culture medium.
US 2006/0160787 discloses N-thiolated beta-lactam compounds and analogs and pharmaceutically acceptable salts, esters and amides thereof. US 2006/0160787 further discloses methods for inducing tumor cell death or inhibiting tumor cell proliferation, and methods for inducing DNA damage, inhibiting DNA replication, activating p38 MAP kinase, or activating caspase cascade activation, or releasing cytochrome C from mitochondria into the cytoplasm in a tumor cell. Methods for treating cancer using N-thiolated beta-lactam compounds, as well as pharmaceutical compositions comprising the same are further disclosed.
LV Patent Application No. 1998000000132 discloses pharmacologically active substances, particularly cytotoxic agents for chemotherapy for cancer. The compounds contain modified penicillin sulfoxide esters or penicillin sulfone esters having specifically selected substituents in position 6 and in the 2-beta-methylgroup.
WO 2007/099396 discloses a therapeutic kit to provide a safe and effective dosage of an antibiotic agent, and a foamable composition including an antibiotic agent, at least one organic carrier, a surface-active agent, at least one polymeric additive and water. WO 2007/099396 further discloses a method of treating, alleviating or preventing disorders of the skin, body cavity or mucosal surface, wherein the disorder involves inflammation as one of its etiological factors, including administering topically to a subject having the disorder, a foamed composition including: an antibiotic agent, inter alia beta-lactam antibiotics, at least one organic carrier, a surface-active agent, a polymeric additive and water. The antibiotic agent includes, inter alia, beta-lactam antibiotics.
U.S. Pat. No. 6,610,681 discloses therapeutic methods using clavulanic acid and related compounds, inter alia, a method for treating a prostate disease selected from prostate cancer and benign prostate hyperplasia in a human patient.
U.S. Pat. No. 6,627,625 discloses therapeutic methods using beta-lactam compounds including beta-lactam antibiotics and beta-lactamase inhibitors, inter alia, a method for treating a prostate disease selected from prostate cancer and benign prostate hyperplasia in a human patient.
Antibiotics not containing beta-lactam moieties have been previously reported to affect apoptosis and cytokine secretion by T cells. Moxifloxacin, a fluoroquinolone antibiotic, was reported to inhibit TNFα and IL-6 secretion by T cells (Choi et al. (2003) Antimicrob Agents Chemother, 47, 3704-3707). Rifampicin, an antibiotic drug of the rifamycin group, was found to inhibit CD95-induced apoptosis by T cells (Gollapudi et al. (2003) J Clin Immunol, 23, 11-22), and macrolide antibiotics were reported to induce apoptosis in T cells (Ishimatsu et al. (2004) Int J Antimicrob Agents, 24, 247-253; and Kadota et al. (2005) Int J Antimicrob Agents, 25, 216-220). Minocycline was found to inhibit TNFα and INFγ (Kloppenburg et al. (1996) Antimicrob Agents Chemother, 40, 934-940), and doxycycline demonstrated anti-inflammatory effects (Krakauer et al. (2003) Antimicrob Agents Chemother, 47, 3630-3633).
Previous work on the effects of antibiotics on experimental autoimmune diseases has shown that minocycline, fucidin and tetracycline could inhibit experimental autoimmune encephalomyelitis (EAE) (Giuliani et al. (2005) J Neuroimmunol, 165, 83-91; Brundula et al. (2002) Brain, 125, 1297-1308; Di Marco et al. (2001) Mult Scler, 7, 101-104; and Popovic et al. (2002) Ann Neurol, 51, 215-223). Oral vancomycin, which is poorly absorbed, was found to inhibit adjuvant arthritis by its effects on the intestinal flora (Nieuwenhuis et al. (2000) Arthritis Rheum, 43, 2583-2589). Tetracycline is used clinically as an immune modulator in patients with Pemphigus and Bullous Pemphigoid (Calebotta et al. (1999) Int J Dermatol, 38, 217-221; and Kolbach et al. (1995) Br J Dermatol, 133, 88-90).
WO 2003/061605 discloses methods for treating a host suffering from a chronic immune disease, e.g., multiple sclerosis or chronic fatigue syndrome. In practicing the subject methods, an effective amount of an elastase inhibitory agent, e.g., a beta-lactam containing compound, is administered to the host. Compositions for use in practicing the subject methods are also disclosed.
WO 1999/024613 reports a newly-identified human blood bacterium which appears to be directly or indirectly associated with several diseases such as chronic fatigue syndrome, multiple sclerosis and other autoimmune diseases. WO 1999/024613 discloses, inter alia, a method for treating a pathophysiological state in an individual having human blood bacterium in the blood, comprising the step of administering to said individual a therapeutically effective amount of at least one antibiotic selected from the group consisting of penicillin G, penicillin V, probenecid, Augmentin, dicloxacillin, Ciprofloxacin, Isoniazid, third-generation cephalosporins, azithromycin, clarithromycin, chloroquin, hydroxychloroquine, minocycline, doxycycline and primaquine.
Nowhere is it disclosed or suggested that certain beta-lactam compounds, including both antibiotics and beta-lactam compounds devoid of anti-bacterial effect, can directly and effectively stimulate T cell activity, and particularly that these beta-lactam compounds can augment tumor rejection. In addition, nowhere is it disclosed or suggested that a similar effect is observed when these beta-lactam compounds are conjugated to a protein, for example, to albumin. There is a medical need for compositions and methods that enhance T cell activity, which may be useful, for example, in cancer therapy.